/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.commons.utils;

import org.apache.iotdb.commons.auth.entity.PathPrivilege;

import java.io.DataInputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;

public class IOUtils {

    private IOUtils() {
    }

    /**
     * Write a string into the given stream.
     *
     * @param outputStream        the destination to insert.
     * @param str                 the string to be written.
     * @param encoding            string encoding like 'utf-8'.
     * @param encodingBufferLocal a ThreadLocal buffer may be passed to avoid frequently memory
     *                            allocations. A null may also be passed to use a local buffer.
     * @throws IOException when an exception raised during operating the stream.
     */
    public static void writeString(
            OutputStream outputStream,
            String str,
            String encoding,
            ThreadLocal<ByteBuffer> encodingBufferLocal)
            throws IOException {
        if (str != null) {
            byte[] strBuffer = str.getBytes(encoding);
            writeInt(outputStream, strBuffer.length, encodingBufferLocal);
            outputStream.write(strBuffer);
        } else {
            writeInt(outputStream, 0, encodingBufferLocal);
        }
    }

    /**
     * Write an integer into the given stream.
     *
     * @param outputStream        the destination to insert.
     * @param i                   the integer to be written.
     * @param encodingBufferLocal a ThreadLocal buffer may be passed to avoid frequently memory
     *                            allocations. A null may also be passed to use a local buffer.
     * @throws IOException when an exception raised during operating the stream.
     */
    public static void writeInt(
            OutputStream outputStream, int i, ThreadLocal<ByteBuffer> encodingBufferLocal)
            throws IOException {
        ByteBuffer encodingBuffer;
        if (encodingBufferLocal != null) {
            encodingBuffer = encodingBufferLocal.get();
            if (encodingBuffer == null) {
                // set to 8 because this buffer may be applied to other types
                encodingBuffer = ByteBuffer.allocate(8);
                encodingBufferLocal.set(encodingBuffer);
            }
        } else {
            encodingBuffer = ByteBuffer.allocate(4);
        }
        encodingBuffer.clear();
        encodingBuffer.putInt(i);
        outputStream.write(encodingBuffer.array(), 0, Integer.BYTES);
    }

    /**
     * Read a string from the given stream.
     *
     * @param inputStream    the source to read.
     * @param encoding       string encoding like 'utf-8'.
     * @param strBufferLocal a ThreadLocal buffer may be passed to avoid frequently memory
     *                       allocations. A null may also be passed to use a local buffer.
     * @return a string read from the stream.
     * @throws IOException when an exception raised during operating the stream.
     */
    public static String readString(
            DataInputStream inputStream, String encoding, ThreadLocal<byte[]> strBufferLocal)
            throws IOException {
        byte[] strBuffer;
        int length = inputStream.readInt();
        if (length > 0) {
            if (strBufferLocal != null) {
                strBuffer = strBufferLocal.get();
                if (strBuffer == null || length > strBuffer.length) {
                    strBuffer = new byte[length];
                    strBufferLocal.set(strBuffer);
                }
            } else {
                strBuffer = new byte[length];
            }

            inputStream.read(strBuffer, 0, length);
            return new String(strBuffer, 0, length, encoding);
        }
        return null;
    }

    /**
     * Read a PathPrivilege from the given stream.
     *
     * @param inputStream    the source to read.
     * @param encoding       string encoding like 'utf-8'.
     * @param strBufferLocal a ThreadLocal buffer may be passed to avoid frequently memory
     *                       allocations. A null may also be passed to use a local buffer.
     * @return a PathPrivilege read from the stream.
     * @throws IOException when an exception raised during operating the stream.
     */
    public static PathPrivilege readPathPrivilege(
            DataInputStream inputStream, String encoding, ThreadLocal<byte[]> strBufferLocal)
            throws IOException {
        String path = IOUtils.readString(inputStream, encoding, strBufferLocal);
        int privilegeNum = inputStream.readInt();
        PathPrivilege pathPrivilege = new PathPrivilege(path);
        for (int i = 0; i < privilegeNum; i++) {
            pathPrivilege.getPrivileges().add(inputStream.readInt());
        }
        return pathPrivilege;
    }

    /**
     * Write a PathPrivilege to the given stream.
     *
     * @param outputStream        the destination to insert.
     * @param pathPrivilege       the PathPrivilege to be written.
     * @param encoding            string encoding like 'utf-8'.
     * @param encodingBufferLocal a ThreadLocal buffer may be passed to avoid frequently memory
     *                            allocations. A null may also be passed to use a local buffer.
     * @throws IOException when an exception raised during operating the stream.
     */
    public static void writePathPrivilege(
            OutputStream outputStream,
            PathPrivilege pathPrivilege,
            String encoding,
            ThreadLocal<ByteBuffer> encodingBufferLocal)
            throws IOException {
        writeString(outputStream, pathPrivilege.getPath(), encoding, encodingBufferLocal);
        writeInt(outputStream, pathPrivilege.getPrivileges().size(), encodingBufferLocal);
        for (Integer i : pathPrivilege.getPrivileges()) {
            writeInt(outputStream, i, encodingBufferLocal);
        }
    }

    /**
     * Replace newFile with oldFile. If the file system does not support atomic file replacement then
     * delete the old file first.
     *
     * @param newFile the new file.
     * @param oldFile the file to be replaced.
     */
    public static void replaceFile(File newFile, File oldFile) throws IOException {
        if (!newFile.renameTo(oldFile)) {
            // some OSs need to delete the old file before renaming to it
            if (!oldFile.delete()) {
                throw new IOException(String.format("Cannot delete old user file : %s", oldFile.getPath()));
            }
            if (!newFile.renameTo(oldFile)) {
                throw new IOException(
                        String.format("Cannot replace old user file with new one : %s", newFile.getPath()));
            }
        }
    }

    public static ByteBuffer clone(ByteBuffer original) {
        ByteBuffer clone = ByteBuffer.allocate(original.capacity());
        original.rewind();
        clone.put(original);
        original.rewind();
        clone.flip();
        return clone;
    }
}
